Introduction and Aim of the work: Behcet's disease (BD) was initially described by the Turkish dermatologist Hulusi Behcet in 1937. It is one of the autoimmune diseases due to a generalized systemic vasculitis and affects all systems. BD has both cochlear and vestibular manifestations on the auditory system. The incidence of hearing loss in BD has been reported to be between 12 to 80%. Inner ear disturbances is the fourth to seventh most common clinical manifestation in BD. Audiologic assessment and management may be helpful for early diagnosis and treatment of patients with BD. The Aim of this work was to study the frequency, type, degree of hearing loss in BD patients and to assess cochlear function using OAE and ECochG aiming at early identification of sub clinical cochlear affection in BD patients. Subjects and Methods: Thirty BD patients and 20 normal controls were examined. Electrocochleography (ECochG) and otoacoustic emissions (TEOAE and DPOAE) were performed. The BD group was subdivided according to three parameters: organs affected by the disease, duration of the disease and activity of the disease. Results: Cochlear pathology in BD patients was centered around the mid and basal turns of the cochlea. These patients also exhibited a subclinical endolymphatic hydrops, which was not affected by activity of the disease or different organ affection but was influenced by duration of the disease. There was no relation between cochlear affection and any organ affection. Conclusion: BD has a definite affection on the auditory system. BD patients demonstrated a sub clinical vestibular hydrops. Cochlear pathology in BD patients was centered around the mid and basal turns of the cochlea. Effect of duration of the disease was mainly on the sub clinical vestibular hydrops rather than cochlear pathology.